1. Field of the Invention
The present invention relates to a micro-chip fuse and a method of manufacturing the same, the micro-chip fuse being utilized for surface mounting on a printed board by using a metallic film as a fusible element.
2. Description of the Prior Art
In recent years, a control unit for an electric appliance in which a fuse is incorporated has been miniaturized to a great extent, and in line with this tendency of miniaturization, the fuse has been miniaturized as well. In the case of a fusible element made of a metallic wire, there is a limitation in the technique in itself of producing a fusible fine wire. Therefore, as to a micro-chip fuse to be applied to a surface mount on a printed board, a fusible element comprised of a metallic film adhered to the surface of the main body made of ceramic material has been proposed. An example of such a fusible element is disclosed in the official gazette of Japanese Patent Laid-open No. 5-166454.
Fusion of a fuse will result from the balance between the heating value generated at the fusible element and the heating value radiated from the fusible element. For this reason, the best construction to keep the pre-arcing time current characteristic of a fuse to be uniform is such a construction in which the fusible element does not contact portions of a fuse other than the electrodes.
A micro-chip fuse is apt to be influenced by external heat due to being extremely small in size. Furthermore, since the fuse as disclosed in the prior art is so constructed that a fusible element is in contact with the main body and other portions, the heat generated at the fusible element may escape from the portions in contact with the fusible element. Also, depending on the structure of a printed board on which a chip fuse is to be surface-mounted, the heat generated at the printed board may be conducted to the fuse, resulting in a change of the characteristics of the fuse. In such a case, the inherent characteristics of the fuse cannot be maintained, resulting in the possibility of damage to the printed board in the worst case.